Ankle joint structure for artificial limbs



March 28, 1939. c. H DAVIES 2,152,402

ANKLE JOINT STRUCTURE FOR ARTIFICIAL LIMBS Filed Dec. 30, 1936 2Sheets-Sheet l March 28, -1939. c. H. DAVIES ANKLE JOINT STRUCTURE FORARTIFICIAL LIMBS Filed Dec. :50, 1956 2 Sheets-Sheet Patented Mar. 28,1939 UNITED STATES PATENT OFFICE Charles H. Davies, Philadelphia, Pa.

Application December 30,1936, Serial No. 118,417

4 Claims.

The present invention relates to improvements in the ankle jointstructure of artificial limbs, whereby appearance and reliability of thejoint are greatly enhanced. Since the invention will be best understoodfrom a detailed description of a specific exemplification, such adescription will be given with reference to the accompanying drawingswhich show a practical embodiment.

In the drawings:

Figure 1 is a side elevation of an artificial limb embodying the presentinvention.

Figure 2 is a perspective view of the ankle portion of the limb at onestage of manufacture.

Figure 3 is a section substantially on line 33 of Figure 1.

Figure 4 is a perspective view of a bearingcarrying fitting or insertforming a part of the ankle joint.

Figure 5 is a bottom plan view of the shin portion' of the limb with thefoot removed.

Figure 6 is a plan view of the rear portion of the foot.

Figure '7 is a longitudinal section of the foot and lower end of theshin portion, and

Figure 8 is an elevation of a modified form of ankle joint bolt andanchoring bolt or sleeve.

Referring to the drawings, reference numeral HI designates the thighportion of an artificial limb, reference numeral II the shin portion,and reference numeral l2 the foot portion. The design of limb is thesame as that shown in my copending application Serial No. 19,897, filedMay 4, 1935, the present application being a continuation in part and,as above stated, being directed to the ankle joint structure.

The thigh and shin portions or sections are of hollow metalconstruction, preferably seamless and formed in a manner such as isdisclosed in 40 my United States Patent 1,884,589, granted October 25,1932. The foot portion may be made of wood or other suitable material.

The lower edges of the shin member are in substantially the same plane,except that the side walls have arcuate downward extensions orcontinuations opposite each other, these being designated at [3 and 14.In the heel portion is set a fitting in the form of an inverted cup-likemember 15, which has side and rear flanges welded to the walls of theshin portion around the heel zone thereof. Member is provided mediallywith an upward offset which provides a recess 16 (Fig. 7). Member l5terminates forwardly at the extensions [3 and I4.

Forwardly of the extensions the side and front Cl. 3-6) I walls of theshin portion are bridged by a fitting in the form of an arcuate plate I!whose margins are butted by the edge of the shin portion, the partsbeing secured together by welding.

The extensions or cars l3 and M are inwardly offset as are also the sidewall portionsthereabove, depressions l8 and I9 being thus formed. Thecars are rimmed by outwardly projecting flanges 20 and 2|, which areturned therefrom 7 and which terminate upwardly at the lower edge of theankle portion as'is most clearly shown in Figure 2. Each of thedepressions has frontwardly and rearwardly extending branches as at l9and I9 Figure 2, and fittings or inserts 22 and 23 are received in therespective recesses, each being shaped as particularly shown in Figure4. In this latter figure, the insert 23 is shown and it Will be observedthat it has a main substantially circular body portion with projectingarms 23 and 23 the insert being positionable in the recess 19 inconforming relation to the latter with arms 23 and 23 in the branches l9and I9 respectively. When thus positioned, the fitting is secured inplace preferably by Welding throughout its perimeter so that the weldingmetal as at 24,

Figure 3, entirely obliterates the joint between the two parts and givesa perfectly smooth finish as in Figure 1.

The fittings 22 and 23 carry in suitable central openings ball bearingassemblies 25 and 26 which may be screwed or pressed into position. Theextensions I3 and M which back the fittings, are centrally pierced toprovide openings through which the reduced ends of a pivot bolt 21 arepassed into the inner races of the bearing assemblies. The ends of thebolt 21 are tapped to receive retaining screws 28 and 29, and if desiredWashers may be interposed between the heads of the screws and the outerends of the inner races. The central portion of bolt 2'! is engaged inthe eye of an anchor bolt or stem 30.

With the described construction the bolt 21 must be sprung intoposition, and unless care is exercised some permanent distortion mayresult. Furthermore, the bolt must be positioned prior to the welding ofthe fittings 22 and 23 in place. Consequently, as a desirablemodification, the pivot bolt may be of the simple form shown in Figure8. The bolt or pin 3| of this figure is cylindrical and of uniformdiameter throughout, the diameter being such that the bolt'may be slidthrough one inner race, then threaded through the eye of the bolt orstem 32, Figure 8, and the entering end then slid into the other innerrace,

retaining screws such as 28 and 29 of Figure 3 being then applied. Whenthus positioned, bolt 32 is secured to bolt 3| by means of a set screw33.

To refer again to Figure 3, the bolt 30, which is secured to pivot bolt21 by means of a set screw 30 has a threaded stem which is passedthrough the foot portion l2 and engaged by a nut34. The foot supports abolster 35, which has two channel portions 36 and 3'! of arcuatecross-section and in which the end portions of bolt 21 are seated,non-metallic or soft metal cushions 38 and 39 being interposed betweenthe bolt and the Channel portions. Bolt 30 extends through the slot 49,which separates the channel portions 36 and 31. The latter have fixed intheir bottom walls upwardly projecting pins or studs 4| and 42, whichengage with a close fit in sockets Ma and 42a in the underside of thepivot bolt so that the latter is securely held against rotation andaxial displacement.

While as above stated, bolt 30 is secured to bolt 21 by means of the setscrew 30*, nevertheless this screw may become loose, and since,moreover, the stem of bolt 30 may wear away or enlarge the bore 43 inthe foot through which it passes, I have provided the pin and socketconnection to insure that the pivot bolt will be held absolutely fixed,the Cradle 35, it will be understood being rigidly fixed on the bottomwall 14 of the foot recess 45 which receives the ankle end of the shinportion.

It will be understood that the pivot and anchor bolt of Figure 8 aredesigned to be associated with the foot portion in exactly the samemanner as the bolts 21 and 30.

An elongated rubber pedestal 46, has one end received in a depression45* in the heel portion of recess 45 and its upper end embraced in therecess 16 of fitting l5 so as to be securely retained in uprightposition. A rubber pad 41 is interposed between plate I! and the forwardbottom wall portion of recess 45.

It will be seen that the lower rear portion Ha of the shin portion isadequately lapped by the heel wall I 2a of the foot, Figure '7. Thislatter wall, however, is sufficiently low so that the top edge of thecounter of the ordinary low shoe will lie sufificiently above the walll2a so as to obscure the break between the latter and the wall portion HDue to the relative low position of the wall portion ll in the footcavity, I have provided the inverted cup-shaped fitting I5 in order thatthe rubber pedestal 46 may be made of suificient lengthto afford therequired yielding support. In other words, I have provided a relativelyelevated abutment for the upper end of the pedestal and by reason ofthis fact, I am enabled to utilize a pedestal of sufiicient length togive proper compression characteristics.

The described ankle structure is entirely silent in use due to thecomplete anchoring of the pivot bolt and to the rigid nature of thebearingcarrying inserts and their rigid association with the shinportion. The lower end of the shin portion is also greatly strengthenedby the welded elements l5 and I! which extend throughout that part ofthe ankle not occupied by the fittings 22 and 23 so that a weldedstructure is present from the front to the rear of the said lower end.

Since changes in form and arrangement may be made from what has beendescribed without departure from the scope of the invention, it will beunderstood that I do not limit myself in these respects, except as inthe following claims.

I claim:

1. An artificial limb comprising a hollow metal shin portion, a fittingclosing the rear portion of the ankle end of said shin portion, afitting closing the forward portion of the ankle end of said shinportion, said fittings being welded in place, side portions of the shinportion depending between said fittings, and bearing-carryingreinforcements fixed to said depending portions.

2. A hollow metal artificial limb having at one end depressions in itsside walls, each of said depressions having frontwardly and rearwardlyextending branches, and bearing-carrying metal inserts received in saidrecesses and having arms extending in said branches, the inserts beingwelded in position.

3. An artificial shin comprising a hollow metal body having at the ankleend depressions in the body side walls at the lower edges of the latter,each depression having frontwardly and rearwardly extending branches,and bearing-carrying metal inserts received in said recesses and having.arms extending in said branches, the inserts being welded inv position.

4. An artificial limb comprising a hollow metal shin portion having inits lower side walls depressions with branch portions extendin f on wrdly and rearwardly, said side walls having substantially semi-circularextensions below said depressions, which extensions are rimmed byoutwardly projecting flanges, and bearing-carryingfittings disposed andwelded .in said depressions and against said extensions and flanges,said fittings having arms extending in said branch portions.

CHARLES H. DAVIES.

